The function of the is to carry information to and from all parts of the body.

I would say the nervous system carries information to and from all parts of the body. The nervous system is what connects the brain to the rest of the body to send signals to different parts for muscle movement, speech, body language etc. 

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.